Filter bag



FIG. 1 is a perspective view of a filter bag showing my new design, the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is a right side elevation view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and

FIG. 7 is a left side elevation view thereof.

The crossline shading which is partially shown is understood to represent conventional fabric and to repeat uniformly across the body of the filter bag. 

The ornamental design for a filter bag, substantially as shown and described. 